From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gabriel de Perthuis Subject: Re: good bcache use case? Date: Tue, 15 Oct 2013 23:12:03 +0200 Message-ID: <525DAFA3.4060709@gmail.com> References: <1005c01cec92f$b61b2040$225160c0$@acm.org> <1381849203.67736.YahooMailNeo@web181503.mail.ne1.yahoo.com> <038e01cec9da$8a19e750$9e4db5f0$@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <038e01cec9da$8a19e750$9e4db5f0$@acm.org> Sender: linux-bcache-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Paul B. Henson" Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-bcache@vger.kernel.org Le 15/10/2013 21:12, Paul B. Henson a =E9crit : >> From: matthew patton [mailto:pattonme-/E1597aS9LQAvxtiuMwx3w@public.gmane.org] Sent: Tuesday,=20 >> October 15, 2013 8:00 AM >>=20 >> Anything shy of the official linux 3.11.5 kernel release has=20 >> several time-bomb bugs. >=20 > Hmm, given 3.10 is an LTS kernel presumably these bug fixes would be=20 > back ported? I suppose it would just be a matter of making sure for > a given 3.10.x that they had been. 3.10.x and 3.11.y stable kernels have been getting bcache backports whenever necessary. 3.11.4 had a regrettable crasher in writeback mode= , but no time-bomb. The confusion may come from the fact that the patch that introduced the crash was fixing a more serious bug. Stopping here because the mailing list is starting to feel like Groundhog day. >> personally would be a bit circumspect in calling it fully=20 >> production ready. I don't believe there are any known significant >> bugs but with the recent flurry of fixes I'd liken it's solidity as >> more pudding rather than cake. >=20 > Well, that's not exactly a ringing endorsement :). I suppose I could=20 > always stick with plan A and migrate to bcache later, it should be=20 > easy enough to pvmove everything off of the SSD raid1, pvremove it,=20 > and then with a little downtime convert the raid10 to a backing > store and the SSD raid1 to a cache. >=20 > Thanks for the opinions. Right now I have in-place conversion for LVs, but not for PVs (details on the bcache wiki). The block layout would work for PV conversions, but since LVM can do raid and a single cache can cache multiple devices= , I've assumed putting bcache on top is preferable. Maybe for people who do a lot of snapshotting the other option is better. (Do as you prefer= , just thinking out loud)